Recently, the major trend in image recording material has been directed to material for color imaging. Specifically, there are employed ink jet printing material, thermal transfer type recording material, recording material using an electrophotography system, transfer type silver halide photographic material, printing inks and recording pens. Color filters are also used in displays such as LCD (liquid crystal display) and PDP (plasma display panel) and in electronic parts such as CCD for use in picture-taking instruments. In these color imaging materials and color filters, dyes and pigments of the three primary colors of a so-called additive mixture system or subtractive mixture system are employed to reproduce or record full color images. However, there is actually no dye which is durable under various conditions for use and an improvement thereof has been desired.
Specifically in inks for use in ink jet printing are desired compatibility with a recording system used, having a relatively high image recording density and superior color tone, superior color image durability such as light fastness, heat fastness and water resistance, rapid fixability onto a recording medium without bleeding, superior storage stability as ink, no problem in safety such as toxicity or inflammability, and low cost.
In light of the foregoing, there have been proposed or studied various inks for ink jet printing but inks meeting many requirements are limited.
In color image recording with yellow, magenta, cyan and black, for example, there have been studied commonly known dyes and pigments having a C.I. number described in the C.I. index. In yellow inks using water-soluble dyes, for example, the use of azo-type water-soluble dyes such as Direct Yellow 96 and C.I. Direct Yellow 132 are known; however, such dyes cause problems that the dyes fall within a short wavelength region and do not easily raise print density, and in addition still have problems in fastness such as light fastness, while being at a higher level than magenta. Magenta inks using xanthene dyes such as C.I. Acid Red 52 or water-soluble azo dyes such as C.I. Direct Red 20 have been known, which exhibit high reliability with respect to clogging caused in a printer, while having problems in fastness such as light fastness and water resistance. There is also known the use of quinacridone pigments such as C.I. Pigment Red 122, which exhibits relatively high color fastness, while producing problems in color reproduction, such as low printing density or bronzing. Color and fastness required for ink jet ink are inconsistent in conventional dyes and pigments.
To overcome the foregoing problems, an azo dye, anthrapyridone compounds and a water-based ink composition containing the same were proposed to improve both color and light fastness, such as yellow inks described in JP-A Nos. 2002-371079 and 2001-311016 (hereinafter, the term, JP-A refers to Japanese Patent Application Publication) and a magenta ink described in JP-A No. 10-306221. However, they are still insufficient in light fastness and an improvement thereof is still desired.